Dabigatran in patients with atrial fibrillation: perioperative and periinterventional management.

In any type of invasive surgery, the patient's individual risk of thromboembolism has to be weighed against the risk of bleeding. Based on various everyday situations in clinical routine, the purpose of the present expert recommendations is to provide appropriate perioperative and periinterventional management for patients with atrial fibrillation undergoing long-term treatment with the thrombin inhibitor dabigatran. As we currently have no routine laboratory test to measure therapeutic levels of the substance or the risk of bleeding, general measures such as a standardized documentation of the patient's history, a sufficient time interval between the last preoperative dose and the procedure, and careful control of local hemostasis should be given special attention.

A signal processing pipeline for noninvasive imaging of ventricular preexcitation.

OBJECTIVES: Noninvasive imaging of the cardiac activation sequence in humans could guide interventional curative treatment of cardiac arrhythmias by catheter ablation. Highly automated signal processing tools are desirable for clinical acceptance. The developed signal processing pipeline reduces user interactions to a minimum, which eases the operation by the staff in the catheter laboratory and increases the reproducibility of the results. METHODS: A previously described R-peak detector was modified for automatic detection of all possible targets (beats) using the information of all leads in the ECG map. A direct method was applied for signal classification. The algorithm was tuned for distinguishing beats with an adenosine induced AV-nodal block from baseline morphology in Wolff-Parkinson-White (WPW) patients. Furthermore, an automatic identification of the QRS-interval borders was implemented. RESULTS: The software was tested with data from eight patients having overt ventricular preexcitation. The R-peak detector captured all QRS-complexes with no false positive detection. The automatic classification was verified by demonstrating adenosine-induced prolongation of ventricular activation with statistical significance (p <0.001) in all patients. This also demonstrates the performance of the automatic detection of QRS-interval borders. Furthermore, all ectopic or paced beats were automatically separated from sinus rhythm. Computed activation maps are shown for one patient localizing the accessory pathway with an accuracy of 1 cm. CONCLUSIONS: The implemented signal processing pipeline is a powerful tool for selecting target beats for noninvasive activation imaging in WPW patients. It robustly identifies and classifies beats. The small beat to beat variations in the automatic QRS-interval detection indicate accurate identification of the time window of interest.

Computationally efficient noninvasive cardiac activation time imaging.

OBJECTIVE: The computer model-based computation of the cardiac activation sequence in humans has been recently subject of successful clinical validation. This method is of potential interest for guiding ablation therapy of arrhythmogenic substrates. However, computation times of almost an hour are unattractive in a clinical setting. Thus, the objective is the development of a method which performs the computation in a few minutes run time. METHODS: The computationally most expensive part is the product of the lead field matrix with a matrix containing the source pattern on the cardiac surface. The particular biophysical properties of both matrices are used for speeding up this operation by more than an order of magnitude. A conjugate gradient optimizer was developed using C++ for computing the activation map. RESULTS: The software was tested on synthetic and clinical data. The increase in speed with respect to the previously used Fortran 77 implementation was a factor of 30 at a comparable quality of the results. As an additional finding the coupled regularization strategy, originally introduced for saving computation time, also reduced the sensitivity of the method to the choice of the regularization parameter. CONCLUSIONS: As it was shown for data from a WPWpatient the developed software can deliver diagnostically valuable information at a much shorter span of time than current clinical routine methods. Its main application could be the localization of focal arrhythmogenic substrates.

Ventricular surface activation time imaging from electrocardiogram mapping data.

Non-invasive imaging of cardiac electrophysiology provides a non-invasive way of obtaining information about electrical excitation. An iterative algorithm based on a general regularisation scheme for non-linear, ill-posed problems in Hilbert scales was applied to the electrocardiographic inverse problem, imaging the ventricular surface activation time (AT) map. This method was applied to electrocardiographic data from a 31-year-old healthy volunteer and a 24-year-old patient suffering from a Wolff-Parkinson-White (WPW) syndrome. The objective was to evaluate non-invasive AT imaging of an autonomous sinus rhythm and to quantify the localisation error of non-invasive AT imaging by localising the accessory pathway of the WPW syndrome and a pacing site for left ventricle pacing. The distances between the invasive and non-invasive localisation of the pacing site and the accessory pathway were 8 mm and 5 mm. The clinical case presented, shows that this non-invasive AT imaging approach may enable the reconstruction of single focal events with sufficient accuracy for potential clinical application.

Electrocardiographic analysis of ectopic atrial activity obscured by ventricular repolarization: P wave isolation using an automatic 62-lead QRST subtraction algorithm.

INTRODUCTION: Atrial activity on the surface ECG during premature beats and supraventricular arrhythmias frequently is obscured by the superimposed QRST complex of the previous cardiac cycle. This study examines the performance of a newly developed automatic QRST subtraction algorithm to isolate ectopic P waves from the preceding T-U wave. METHODS AND RESULTS: The 62-lead ECG recordings were obtained during (1) sinus rhythm and programmed right atrial stimulation in 12 patients (group A); and (2) sinus rhythm and atrial premature beats, atrial tachycardia, or paroxysmal atrial fibrillation in 5 patients (group B). Pacing in group A patients was conducted at a slow drive cycle length to generate an ectopic P wave not obscured by the previous QRST complex and by delivering single premature extrastimuli at progressively shorter coupling intervals to produce an ectopic P wave obscured by the upsloping (early T-U wave), peak (middle T-U wave), and downsloping component of the T-U wave (late T-U wave). All ectopic P waves in group B patients were concealed by the preceding T-U wave. Automatic QRST subtraction was attained using an adaptive template constructed from averaged QRST complexes (mean 83 +/- 25 complexes) obtained during sinus rhythm (groups A and B) or atrial overdrive pacing (group A). P wave integral maps subsequently were computed, visually compared, and mathematically correlated. A high correspondence in spatial map pattern was observed between integral maps of "nonobscured" and previously "obscured" paced P waves obtained in group A patients (mean r = 0.88 +/- 0.07) as well as between integral maps of two to three previously obscured P waves with the same atrial arrhythmia morphology obtained in group B patients (mean r = 0.94 +/- 0.05). Improved morphologic P wave replication in group A patients was acquired when concealment occurred in the early (mean r = 0.90 +/- 0.08) or late part of the T-U wave (mean r = 0.90 +/- 0.06) as opposed to the middle T-U wave (mean r = 0.85 +/- 0.07) (P = NS and P < 0.05 for early vs middle and late vs middle T-U wave, respectively). CONCLUSION: This novel automatic 62-lead QRST subtraction algorithm enables discrete isolation of T-U wave obscured ectopic atrial activity on the surface ECG while retaining the intricate spatial detail in P wave morphology. Future clinical application of the algorithm may enable improved ECG localization of focal triggers of paroxysmal atrial fibrillation, atrial tachycardia, and the atrial insertion of accessory pathways.

The effect of the atrial pacing site on the total atrial activation time.

The effect of dual site pacing for prevention of atrial fibrillation may be due to synchronization of right and left atrial activation. Little is known, however, about the effect of pacing from single right atrial sites on differences in interatrial conduction. Twenty-eight patients without structural heart disease were studied following radiofrequency catheter ablation of supraventricular arrhythmias. Pacing was performed using standard multipolar catheters from the presumed insertion site of Bachmann's bundle, the coronary sinus ostium, the high lateral right atrium, and the right atrial appendage (n = 8 patients). Bipolar recording was performed from the distal coronary sinus, the high and low lateral right atrium, and the posterolateral left atrium (n = 13 patients). The longest conduction time from each pacing to each recording site was considered the total atrial activation time for the respective pacing site. During high right atrial pacing, the total atrial activation time was determined by the conduction to the distal coronary sinus (118 +/- 18 ms), during coronary sinus ostium pacing by the conduction to the high right atrium (94 +/- 18 ms), and during Bachmann's bundle pacing by the conduction to the distal coronary sinus (74 +/- 18 ms). The total atrial activation time was significantly shorter during pacing from Bachmann's bundle, as compared to pacing from other right atrial sites. Thus, in normal atria, pacing from the insertion of Bachmann's bundle causes a shorter total atrial activation time and less interatrial conduction delay, as compared to pacing from other right atrial sites. These findings may have implications for alternative pacing sites for prevention of atrial fibrillation.

Body surface mapping of counterclockwise and clockwise typical atrial flutter: a comparative analysis with endocardial activation sequence mapping.

OBJECTIVES: This study was directed at developing spatial 62-lead electrocardiogram (ECG) criteria for classification of counterclockwise (CCW) and clockwise (CW) typical atrial flutter (Fl) in patients with and without structural heart disease. BACKGROUND: Electrocardiographic classification of CCW and CW typical atrial Fl is frequently hampered by inaccurate and inconclusive scalar waveform analysis of the 12-lead ECG. METHODS: Electrocardiogram signals from 62 torso sites and multisite endocardial recordings were obtained during CCW typical atrial Fl (12 patients), CW typical Fl (3 patients), both forms of typical Fl (4 patients) and CCW typical and atypical atrial Fl (1 patient). All the Fl wave episodes were divided into two or three successive time periods showing stable potential distributions from which integral maps were computed. RESULTS: The initial, intermediate and terminal CCW Fl wave map patterns coincided with: 1) caudocranial activation of the right atrial septum and proximal-to-distal coronary sinus activation, 2) craniocaudal activation of the right atrial free wall, and 3) activation of the lateral part of the subeustachian isthmus, respectively. The initial, intermediate and terminal CW Fl wave map patterns corresponded with : 1) craniocaudal right atrial septal activation, 2) activation of the subeustachian isthmus and proximal-to-distal coronary sinus activation, and 3) caudocranial right atrial free wall activation, respectively. A reference set of typical CCW and CW mean integral maps of the three successive Fl wave periods was computed after establishing a high degree of quantitative interpatient integral map pattern correspondence irrespective of the presence or absence of organic heart disease. CONCLUSIONS: The 62-lead ECG of CCW and CW typical atrial Fl in man is characterized by a stereotypical spatial voltage distribution that can be directly related to the underlying activation sequence and is highly specific to the direction of Fl wave rotation. The mean CCW and CW Fl wave integral maps present a unique reference set for improved clinical detection and classification of typical atrial Fl.

Use of electroanatomic mapping to delineate transseptal atrial conduction in humans.

BACKGROUND: Interaction between wave fronts in the right and left atrium may be important for maintenance of atrial fibrillation, but little is known about electrophysiological properties and preferential routes of transseptal conduction. METHODS AND RESULTS: Eighteen patients (age 44+/-12 years) without structural heart disease underwent right atrial electroanatomic mapping during pacing from the distal coronary sinus (CS) or the posterior left atrium. During distal CS pacing, 9 patients demonstrated a single transseptal breakthrough near the CS os, 1 patient in the high right atrium near the presumed insertion of Bachmann's bundle and 1 patient near the fossa ovalis. The mean activation time from stimulus to CS os was 48+/-15 ms compared with 86+/-15 ms to Bachmann's bundle insertion (P<0.01) and 59+/-23 ms to the fossa ovalis (P=NS and P<0.01, respectively). During left atrial pacing, the earliest right atrial activation was near Bachmann's bundle in 5 and near the fossa ovalis in 4 patients. The activation time from stimulus to CS os was 70+/-15 ms compared with 47+/-16 ms to Bachmann's bundle (P<0.01) and 59+/-25 ms to the fossa ovalis (P=NS). Whereas the total septal activation time was not significantly different during CS pacing compared with left atrial pacing (41+/-16 versus 33+/-17 ms), the total right atrial activation time was longer during CS pacing (117+/-49 versus 79+/-15 ms; P<0.05). CONCLUSIONS: Three distinct sites of early right atrial activation may be demonstrated during left atrial pacing. These sites are in accord with anatomic muscle bundles and may have relevance for maintenance of atrial flutter or fibrillation.

The spatial dispersion of atrial refractoriness and atrial fibrillation vulnerability.

The local dispersion of conduction and refractoriness has been considered essential for induction of atrial arrhythmias. This study sought to determine whether a difference of refractoriness and vulnerability for induction of atrial fibrillation between trabeculated and smooth as well as high and low right atrium may contribute to initiation of atrial fibrillation in dogs. In 14 healthy mongrel dogs weighing 22.4 +/- 1 kg, closed-chest endocardial programmed stimulation was performed from four distinct right atrial sites. Atrial refractory periods and vulnerability for induction of atrial fibrillation or premature atrial complexes were determined during a basic cycle length of 400 and 300 ms and an increasing pacing current strength. For a pacing cycle length of 300 ms, atrial refractory periods were longer on the smooth, as compared to the trabeculated right atrium (102 +/- 25 vs. 97 +/- 17 ms, p < 0.05), whereas for a pacing cycle length of 400 ms, there was no significant difference. The duration of the vulnerability zone for induction of atrial fibrillation was longer on the smooth right atrium, for a cycle length of both 400 ms (40 +/- 30 vs. 31 +/- 22 ms; p < 0.05) and 300 ms (33 +/- 25 vs. 23 +/- 21 ms; p < 0. 01). When comparing high and low right atrium, refractory periods were longer on the the low right atrium, for a cycle length of both 400 ms (111 +/- 23 vs. 94 +/- 24 ms; p < 0.01) and 300 ms (104 +/- 20 vs. 96 +/- 23 ms; p < 0.01). For a pacing cycle length of 300 ms, the duration of the atrial fibrillation vulnerability zone was longer for the high, as compared to the low right atrium (34 +/- 22 vs. 22 +/- 22, p < 0.01). Seven dogs with easily inducible episodes of atrial fibrillation demonstrated significantly shorter refractory periods as compared to 7 non-vulnerable dogs, regardless of pacing site and current strength. In conclusion, significant differences in refractoriness and vulnerability for induction of atrial fibrillation can be observed in the area of the crista terminalis in healthy dogs. Thus, local anatomic factors may play a role in the initiation of atrial fibrillation.

Low-power radiofrequency application and intracardiac echocardiography for creation of continuous left atrial linear lesions.

INTRODUCTION: Continuity of radiofrequency (RF) lesions for a catheter-based cure of atrial fibrillation is essential in order to avoid reentrant tachycardias. In the present study, we assessed the value of intracardiac echocardiography and preablation electrode-tissue interface parameters for creation of left atrial linear lesions. METHODS AND RESULTS: In six healthy dogs, two left atrial linear lesions (lesion 1, along the inferior posterior left atrium; lesion 2, from the appendage to the left atrial roof) were attempted via a transseptal approach using a deflectable catheter with six 7-mm coil electrodes. In a randomized fashion, one lesion was performed under echocardiographic guidance and one with blinded echocardiographic monitoring. The following preablation parameters were assessed for every coil electrode: (1) mean atrial electrogram amplitude of six consecutive sinus beats; (2) diastolic pacing threshold; and (3) temperature response to application of 5 W for 10 seconds. After ablation (target temperature 70 degrees C, maximum power 50 W, duration 60 sec), the excised left atrium was examined macroscopically and histologically for lesion length, continuity, and presence or absence of lesions associated with each coil. Out of 12 attempted RF lesions, 7 were continuous (length, 47+/-5 mm, lesion 2, n = 6) and 5 were discontinuous (lesion 1, n = 5). Fifty-two of 70 coil electrodes (74%) had pathologic evidence of lesion creation. Intracardiac echocardiography was superior to fluoroscopy with respect to the actual number of coil electrodes creating lesions, and lesion continuity was correctly predicted in 9 of 12 lesions. Intracardiac echocardiography was 85% sensitive and 54% specific in predicting lesions created by individual coils. The correlation between the mean 60-second ablation temperature and the preablation parameters was 0.45 for the electrogram amplitude, -0.67 for the pacing threshold, and 0.81 for the temperature response to low-power application. Sensitivity and specificity for prediction of lesions created by individual coils, respectively, were 84% and 48% for the electrogram amplitude, 90% and 68% for the pacing threshold, and 96% and 76% for the low-power RF application. CONCLUSION: Long linear lesions can be safely and effectively performed in the canine left atrium, using a tip-deflectable multielectrode catheter. Intracardiac echocardiography may be helpful for positioning the ablation catheter in some parts of the left atrium, and preablation parameters, especially a nontraumatic low-power RF application, are able to predict ultimate lesion creation with high accuracy.

What is the relationship of atrial flutter and fibrillation?

Animal models and human studies of atrial activation mapping and entrainment have considerably enhanced our understanding of the anatomical substrate for atrial flutter and created the basis for a definite cure with radiofrequency catheter ablation. As atrial flutter has now become a curable arrhythmia, emphasis is shifting to understand the most common arrhythmia: atrial fibrillation. Furthermore, from clinical observation, it is apparent that there is a relationship between atrial fibrillation and atrial flutter in patients with atrial arrhythmias. Techniques that have informed our understanding of the anatomical basis of atrial flutter may also be useful in understanding the relationship between atrial fibrillation and flutter, including animal models, clinical endocardial mapping, and intracardiac anatomical imaging. Thus, atrial anatomy and its relationship to electrophysiological findings, and the role of partial or complete conduction barriers around which reentry can and cannot occur, may be of importance for atrial fibrillation as well. Ultimately, the relationship between atrial fibrillation and atrial flutter may inform our understanding of the mechanisms of atrial fibrillation itself, and help to develop new approaches to device, catheter-based, and pharmacological therapy for atrial fibrillation.

Electrophysiologic effects of selective right versus left atrial linear lesions in a canine model of chronic atrial fibrillation.

INTRODUCTION: Long linear lesions have been shown to eliminate atrial fibrillation in animal models, but little is known about the electrophysiologic response in one atrium to lesions in the contralateral atrium. METHODS AND RESULTS: Twelve dogs with chronic atrial fibrillation were randomized to either right atrial ablation (n = 4), left atrial ablation first (n = 4), or a sham procedure (n = 4). Simultaneous biatrial endocardial mapping was performed before and after three linear lesions were applied at specific points in either atrium, using an expandable ablation catheter. Atrial fibrillation was reinducible after single atrial ablation in each dog and no longer inducible after biatrial ablation in five dogs. At baseline, the mean atrial fibrillation cycle length was longer on the trabeculated (117+/-15 msec) compared with the smooth right (101+/-16 msec) or left atrium (88+/-10 msec; P < 0.01). Single right and left atrial ablation caused a significant cycle length increase in the ablated atrium. Left atrial ablation increased the cycle length on both the trabeculated (121+/-18 msec vs 137+/-11 msec; P < 0.05) and smooth right atrium (108+/-12 msec vs 124+/-9 msec; P < 0.05). Right atrial ablation, however, had no significant effect on left atrial fibrillation cycle length (82+/-8 msec vs 86+/-7 msec). CONCLUSION: Left atrial linear lesions affect right atrial endocardial activation, whereas right atrial lesions do not affect left atrial activation in a canine model of atrial fibrillation. These findings suggest that the left atrium is the driver during chronic atrial fibrillation in this animal model and may explain the limited success of right atrial ablation alone in human atrial fibrillation.

[Effects of limited mouth opening capacity (trismus) on lung function]. / Auswirkungen der eingeschränkten Mundöffnung (Kieferklemme) auf die Lungenfunktion.

In the present study pulmonary function test data were obtained from 15 healthy volunteers and 15 patients with slightly impaired ventilation during both normal and maximally reduced opening of the mouth (trismus, intercuspid position). The aim of the study was to examine the effects of complete trismus on pulmonary function using objective and subjective parameters. In maximally reduced mouth opening, both groups showed an impairment of all subjective and objective pulmonary function test data. In healthy volunteers, the significant changes in the test data (p < 0.05) simulated mild to moderate pulmonary impairment, whereas patients with an already impaired pulmonary function showed a marked deterioration of their initial respiratory condition. The results of the subjective and objective parameters examined indicate that an intercuspid position (trismus) further aggravates pulmonary functional impairments. Complete trismus can be considered a risk factor to pulmonary function in patients using mouth-breathing as primary or supportive mode of respiration.

Organized activation during atrial fibrillation in man: endocardial and electrocardiographic manifestations.

INTRODUCTION: Atrial fibrillation is not entirely random, but little is known about the spatiotemporal endocardial organization and its surface ECG manifestations. METHODS AND RESULTS: In 16 patients with atrial fibrillation (chronic, n = 14), endocardial mapping of the trabeculated, the posteroseptal smooth right atrium, and the coronary sinus was performed using multipolar catheters. The surface ECG was analyzed by determining "fibrillation wave" (F wave) amplitude, rate, and polarity. During 50 minutes of atrial fibrillation, an organized activation was present 72% +/- 32% of the analyzed time on the trabeculated, 19% +/- 15% on the smooth right atrium (P < 0.01), and 51% +/- 33% along the coronary sinus (P < 0.05). The direction of organized activation was craniocaudal in 72% +/- 16%, caudocranial in 10% +/- 9% (P < 0.01), and indeterminable in 18% +/- 11%. The mean surface F wave amplitude in lead V1 was 0.128 +/- 0.06 mV during 28 seconds of atrial fibrillation with a craniocaudal direction of activation and 0.065 +/- 0.02 mV during a disorganized activation (P < 0.01). A stable relation between surface F waves and organized trabeculated right atrial activation was observed, and the mean F wave cycle length (190 +/- 27 msec) was highly comparable to the simultaneously measured endocardial cycle length (191 +/- 27 msec, correlation coefficient 0.97). F wave polarity in V1 was positive in 12 of 14 patients during craniocaudal and negative in 11 of 14 patients during caudocranial right atrial free-wall activation. CONCLUSION: An organized activation during atrial fibrillation with a predominant craniocaudal direction on the trabeculated right atrium is frequently present and influences the appearance of "coarse" or "fine" atrial fibrillation as well as F wave polarity on the surface ECG.

Body surface mapping of atrial arrhythmias: atlas of paced P wave integral maps to localize the focal origin of right atrial tachycardia.

Successful curative treatment of right atrial tachycardia (AT) can be obtained provided detailed catheter activation mapping of the target site for radiofrequency energy application has been accomplished. However, right AT mapping may be difficult with a single roving catheter due to infrequent presence or noninducibility of the arrhythmia. The present report describes the preliminary clinical use of body surface mapping as an adjunctive noninvasive method to identify the region of AT origin prior to catheter ablation. This technique has been previously applied to develop a reference data base of 17 different paced P wave integral map patterns. The data base was designed by performing right atrial pace mapping in patients without structural heart disease. Each P wave integral map pattern in the data base is unique to ectopic activation onset in a circumscribed right atrial endocardial segment. Localization of the segment of AT origin is accomplished by matching the P wave integral map of a single AT beat with the data base of paced P wave integral maps. The use of body surface mapping as an integral part of the mapping protocol during radiofrequency catheter ablation of right AT offers the possibility to: (1) noninvasively determine the arrhythmogenic target area for ablation using a single beat analysis approach; (2) confine detailed catheter activation mapping to a limited area; and (3) accelerate the overall procedure and limit fluoroscopic exposure by reducing the time required for mapping.

Relationship between atrial fibrillation and typical atrial flutter in humans: activation sequence changes during spontaneous conversion.

BACKGROUND: A transitional rhythm precedes the spontaneous onset of atrial flutter in an animal model, but few data are available in man. METHODS AND RESULTS: In 10 patients, 16 episodes of atrial fibrillation (166+/-236 seconds) converting into atrial flutter during electrophysiological evaluation were analyzed. A 20-pole catheter was used for mapping the right atrial free wall. Preceding the conversion was a characteristic sequence of events: (1) a gradual increase in atrial fibrillation cycle length (150+/-25 ms after onset, 166+/-28 ms before conversion, P<.01); (2) an electrically silent period (267+/-45 ms); (3) "organized atrial fibrillation" (cycle length, 184+/-24 ms) with the same right atrial free wall activation direction as during atrial flutter; (4) another delay on the lateral right atrium (283+/-52 ms); and (5) typical atrial flutter (cycle length, 245+/-38 ms). The coronary sinus generally had a different rate than the right atrial free wall until the beat that initiated flutter, when right atrium and coronary sinus were activated in sequence. During 1313 seconds of fibrillation, there were 171 episodes of "organized atrial fibrillation." An additional activation delay at least 30 ms longer than the mean organized atrial fibrillation cycle length was sensitive (100%) and specific (99%) for impending organization into atrial flutter. During organized atrial fibrillation, right atrial free wall activation was craniocaudal in 70% and caudocranial in 30%, which may explain why counterclockwise flutter is a more common clinical rhythm than clockwise flutter. Atrial flutter never degenerated into fibrillation, even after adenosine infusion. CONCLUSIONS: Anatomic barriers, along with statistical properties of conduction and refractoriness during atrial fibrillation, may explain the remarkably stereotypical pattern of endocardial activation during the initiation of atrial flutter via fibrillation and the rarity of degeneration of flutter to fibrillation once it stabilizes.

Potential role of 'hybrid therapy' for atrial fibrillation.

Atrial fibrillation is the most common sustained arrhythmia in clinical practice. Several new non-pharmacological technologies are emerging which may offer hope for effective therapy and quality of life improvement of patients with atrial fibrillation. While both catheter-based atrial segmentation and implanted atrial defibrillators have the potential to revolutionize the treatment of patients with atrial fibrillation, both are also associated with the potential for significant limitations. Catheter ablation with the goal of curing atrial fibrillation may be a lengthy procedure and if left atrial lesions are required there is the potential for complications. As regards implanted atrial defibrillators an important question is whether many patients will tolerate the discomfort associated with energy levels required to restore sinus rhythm. The concept of 'hybrid therapy' is that in a given patient a combination of modalities might be used so as to achieve a synergistic effect, with each technology improving the efficacy of the other. For example, the presence of a more 'organized' pattern of fibrillation implies a lower defibrillation threshold. Data in a canine model of atrial fibrillation suggests that linear lesions in the right atrium alone may organize the atrial fibrillation in both atria and in so doing lower the atrial defibrillation threshold. Hybrid therapy may also employ drugs and pacing in combination with ablative lesions and an implanted atrial defibrillator.

[Ventricular septal rupture after blunt chest trauma]. / Ventrikelseptumruptur nach stumpfem Thoraxtrauma.

HISTORY AND CLINICAL FINDINGS: Case 1: a 20-year-old previously healthy man sustained multiple nonvascular injuries without visible chest trauma in a car accident. Four days later a loud systolic murmur was heard over the heart. Case 2: a 21-year-old man similarly sustained in a car accident multiple injuries without visible chest involvement but causing haemorrhagic shock. A loud systolic heart murmur was heard and after shock treatment he developed left heart failure requiring catecholamine infusions. INVESTIGATIONS: Echocardiography demonstrated posttraumatic ventricular septal rupture in both patients. Cardiac catheterisation revealed a small left to right (1 : 1.6) shunt in case 1, and a large one, 1 : 3, with markedly elevated pulmonary artery pressure in case 2. COURSE: In case 1, no treatment was needed as the intracardiac shunt was small and there were no symptoms. But in case 2 the large shunt with pulmonary hypertension required operative closure with a Dacron patch 2 days after the diagnosis had been established. CONCLUSION: Ventricular septal rupture after blunt trauma to the chest is a rare occurrence. Even though in general the prognosis is good, a large intracardiac shunt may require early surgical repair.